This invention generally relates to a flashlight control apparatus for an endoscope, and more particularly, to a flashlight control apparatus for an endoscope in which a solid-state image sensor is employed and an exposure time required for high-speed flash photography is pre-calculated based upon a received photo-metric signal from the solid-state image sensor.
The development of the solid-state image sensor has opened the door to substantial progress in the state of the art of high resolution, compactness and small power consumption.
It is generally desirable to automatically control an exposure time of the flashlight by means of an automatic exposure control device when photographing diseased portions in a patent, by utilizing an endoscope. In the automatic exposure control device of the type mentioned, an automatic exposure control operation is effected in such a manner that when an exposure of light reflected from the diseased portions (foreground subject) becomes a predetermined level, the flashlight is forcibly interrupted by an electronics means.
In the case when the known automatic exposure device is employed in the endoscope, there are provided various disadvantages in that a complex optical system, e.g., a beam splitter is necessarily required, resulting in a bulky in size and expensive cost.
A primary object of the present invention is to realize automatic exposure photography, by use of a flashlight, with an endoscope in which a solid-state image sensor is assembled.
A secondary object of the present invention is to realize high-speed flashlight photography for diseased portions, e.g. a stomach, the motion of which is rapidly changed, with an endoscope in which a solid-state image sensor is assembled.
A third object of the present invention is to provide a flashlight control apparatus for an endoscope in which a solid-state image sensor is employed as a photo-metric optical element as well as a photographing element, so that the camera unit employing the solid-state image sensor becomes compact.
A fourth object of the present invention is to provide a flashlight control apparatus for an endoscope in which a solid-state image sensor is employed so that precise optical adjustment e.g. an alignment of the photo-metric optical system is avoided.